<fieldset>

legend

<form action="/action_page.php">
 <fieldset>
  <legend>Personalia:</legend>
  <label for="fname">First name:</label><input type="text" id="fname" name="fname"><br><br>
  <label for="lname">Last name:</label><input type="text" id="lname" name="lname"><br>
 </fieldset>
</form>